四维血流磁共振成像技术在颅内动脉狭窄卒中患者血流动力学评估中的应用探索

The hemodynamic assessment in ischemic stroke patients with intracranial artery stenosis by using 4D flow magnetic resonance imaging

目的探索四维血流磁共振成像(4D flow MRI)技术在颅内动脉狭窄血流评估中应用的可行性及临床价值。方法前瞻性纳入2017年3月至2018年6月于北京清华长庚医院卒中中心连续收治的症状性单侧大脑中动脉狭窄卒中患者,利用时间飞跃法磁共振血管成像及4D flow MRI技术对其梗死区责任血管的狭窄程度及狭窄近端血流进行定量分析,探索狭窄程度与前向血流的定量关系;对软脑膜侧支进行评分(总分0~3分),联合磁共振灌注成像比较不同侧支状态下狭窄近端残余前向血流与远端脑组织灌注的关系。结果共纳入符合条件的症状性大脑中动脉狭窄患者33例,平均年龄56岁,男性21例(63.6%)。不同狭窄程度(<30%、30%~49%、50%~69%和≥70%)下大脑中动脉血流率分别为(3.56±1.08)、(2.96±0.94)、(3.72±0.60)、(2.50±1.03)ml/s,各组间大脑中动脉病变近端血流率存在显著差异,狭窄程度≥70%时血流率下降最显著(F=4.34,P=0.008);狭窄近端前向血流与灌注的关系提示大脑中动脉狭窄近端残余前向血流与远端脑组织灌注的关系在不同侧支状态存在差异。当远端侧支较差时(侧支评分0~2分),狭窄近端残余血流绝对值及相对值与远端脑组织灌注参数相对达峰时间存在显著负相关(r=-0.76、-0.61,均P<0.05)。结论4D flow MRI技术可用于颅内动脉狭窄患者的血流定量评估,狭窄近端残余前向血流与远端灌注的关系受侧支状态的影响。

Objective To investigate the feasibility and clinical value of 4D flow magnetic resonance imaging(MRI)in evaluating hemodynamics of ischemic stroke patients with intracranial artery stenosis.Methods Ischemic stroke patients with unilateral middle cerebral artery stenosis admitted from March 2017 to June 2018 in Beijing Tsinghua Changgung Hospital Stroke Center were prospectively enrolled.Time of flight magnetic resonance angiography was used to evaluate vascular stenosis,4D flow MRI was used to measure net forward flow at the proximal of stenosis,and brain tissue perfusion was acquired simultaneously to validate flow.Results A total of 33 patients with symptomatic middle cerebral artery stenosis were included[mean age:56 years;male:63.6%(n=21)].The flow rates among patients with stenosis of<30%,30%-49%,50%-69%and≥70%were(3.56±1.08),(2.96±0.94),(3.72±0.60)and(2.50±1.03)ml/s individually,demonstrating a decreased flow in subjects with severe(≥70%)stenosis(F=4.34,P=0.008).Further analysis about forward flow and brain tissue perfusion showed that the significant negative correlation between absolute flow rate or relative flow rate and relative time to peak could only be established in subjects with poor collateral(collateral score:0-2),with r=-0.76 and-0.61 individually,both P<0.05.Conclusion 4D flow MRI could be used as a quantitative flow assessment in subjects with intracranial artery stenosis,and its association with distal brain tissue perfusion depends on collateral status.